"One of the most insidious things happening in the debate is people claiming versions of 'other industries may have problems with sexism, but our industry doesn't,'" he wrote. "Both men and women claim this, even though it keeps getting harder to do in the face of shocks like the Tinder texts."

Altman went on to say diversity, especially gender diversity, is important because he believes women will found some of the most important startups in the future. And he pulled from Y Combinator's stats to back this up.

According to the post, the accelerator accepts a higher percentage of applying technical women than men, though more men apply in total. Altman reports that of the 25% of startups who apply to Y Combinator with women founders, almost 20% are accepted. In a separate post, Altman wrote Y Combinator has a very low acceptance rate, so this isn't too bad. He also reports that of all the YC companies worth more than $100 million, 10% are led by female CEOs.

Besides touting numbers and percentages, Altman also detailed some advice he gives to startups to help curb the sexism so prevalent in his industry. Though many startups wait until they have 50 employees or more before investing in human resources infrastructure, he thinks this is far too late.

"Our sense is that many will benefit by doing it earlier. Traditionally, startups have thought of HR as a drag on moving fast and openness, but a well-running team is one of the best assets a company can ever have," Altman writes.

He says Y Combinator has plans involving this concept in process, but isn't sharing details yet.